Web turning and guiding apparatus

ABSTRACT

An air bar is provided in the path of web travel to change the direction of travel and the air bar position is automatically adjusted to compensate for minor lateral changes in the path of web travel. The web is laterally constrained a short distance downstream of the air bar and the constraining means is adapted to move simultaneously with the air bar in order that when the air turning bar moves to make a correction in web position, the web will move simultaneously by the same amount.

United States Patent Hamlin et al. [451 July 25, 1972 WEB TURNING ANDGUIDING 2,900,934 8/1959 Judelson ..226/l97 x APPARATUS [72] Inventors:Primary Examiner-Allen N. Knowles David R. Hamlin, Rochester; William A.,Torpey, Scottsville, both of NY. 1

Eastman Kodak Company, Rochester, NY.

Feb. 1, 1971 Assignee:

Filed:

Appl. No.:

References Cited Attorney-William T. French, Spencer L. Blaylock andRobert F. Crocker 57 ABSTRACT An air bar is provided in the path of webtravel to change the direction of travel and the air bar position isautomatically adjusted to compensate for minor lateral changes in thepath of web travel. The web is laterally constrained a short distancedownstream of the air bar and the constraining means is adapted to movesimultaneously with the air bar in order that when the air turning barmoves to make a correction in web position, the web will movesimultaneously by the same amount.

11 Claims, 4 Drawing Figures PAIEIEJMS m2 SHEET 1 BF 2 Control DAVID R.HAML/N W/LL/AM A. TORPEY INVENTORS ATTORNEY PAJIENIEML 25 m2 sun-:1 2 or2 DAV/0 R HAMLIN W/L L/AM A. TORPEY INVENTORS WEB TURNING AND GUIDINGAPPARATUS FIELD OF THE INVENTION This invention relates generally to aweb turning apparatus and more particularly to anair cushion, webturning and guiding device useful for inverting, changing the directionof the BACKGROUND OF THE INVENTION In the manufacture or processing ofwebs, particularly webs which are coated with materials subject toscratching, it has been the practice during manufacture to change thedirection of web travel by passing the web around an air turning bar. Inthe customary operation, the web, during passage from one coating ordrying alley or machine to a parallel coating or drying alley, has itsdirection changed twice by passing around a pair of angularly arrangedturning bars. The web, as it passes partially around the first turningbar, changes its direction by some angle, usually 90. Thus, by passingaround a second appropriately arranged turning bar, the direction oftravel of the outgoing web is laterally displaced and is parallel to theincoming web. Likewise, suitable configurations, of air bars are oftenused to invert moving webs.

Highly polished bars are commonly used as turning bars to change thedirection of travel of a web. These turning bars are unsatisfactory forphotographic film because the film is scratched as it slides on theturning bar. For photographic film, the web turning bars are air-cushionbars to prevent scratches or other damage to the film during changes indirection. These web turning bars are in the form of porous, slotted,perforated, or otherwise permeable tubes through which air is passed tomaintain a thin cushion of air between the web and the bar. In somecases, the air cushion turning bars are movably supported for controlledmovement to compensate for minor changes in the lateral position or pathof the web in order that the position of the web leaving the turning baris controlled at the desired location. Such a turning bar is termed asteerable air turning bar.

In order for the web to change its direction and to maintain eventension across the web, the angle of the incoming web path to the axisof the turning bar must be equal to the angle of the outgoing path tothe axis ofthe turning bar.

In order to make the minor adjustments in the position of the steerableair turning bar, the bar is connected to an electric, hydraulic orpneumatic actuator. The controller for such actuators responds tosignals from one or more edge sensors located a short distancedownstream of the turning bar. The edge sensor detects changes in thelateral position or path of the moving web. When the incoming webchanges its position on the turning bar as the result of some upstreamoccurrence, the position of the outgoing web is also changed. Thischange is detected by the edge sensor, which causes the controlleroutput to change, which in turn causes the actuator to reposition thesteerable turning bar in order that the outgoing web position is broughtback to its desired location.

Many of these devices have functioned satisfactorily, however, theperformance of many and perhaps all could be improved. Problems havearisen particularly in those types of situations where the web is passedpartially around a roller or otherwise laterally constrained a shortdistance downstream of the turning bar. Also in the opposite type ofsituation where there is a long span of web downstream of the turningbar with little or no lateral constraint on the web in this span. In thefirst type of situation, the downstream constraint prevents the span ofweb at the turning bar from moving simultaneously with and by the sameamount as the air bar, when the air bar moves in an attempt to properlyposition the web. Since the web position does not instantly follow theposition of the air bar as it is moved, the stability of the controlsystem and the performance of the web guiding system are reduced. Also,since the web position does not instantly and completely follow theposition of the air bar, the web, at times, will follow a skewed path asit passes around the air bar. The skewed path distorts the tensionprofile of the web with the result that one edge may be dragged intocontact with the turning bar, thereby damaging the web. The distortedtension profile may produce slack along the opposite edge of the web,which can cause errors in the sensing of web position. Since the webguiding system is a feed-back system, errors in the sensing of webposition cause extraneous movement of the guider.

In the type of situation where there is a long span of web downstream ofthe turning bar with little or no lateral constraint on the web in thisspan, another problem may occur with the conventional steerable turningbar. In this situation,

there is little attenuation of disturbances in web position in this spanof web. Such disturbances will always be present when web is beingconveyed, and because of the small amount of attenuation present, thesedisturbances may become large and may alter the position of the web onthe steerable turning bar, reducing its effectiveness. They may alsoaffect the position of the web at the sensor, causing the turning barweb guiding system to make extraneous steering corrections. Theseextraneous changes in turning bar position may in turn produceadditional disturbances in the position of the downstream span of web,which may cause additional extraneous steering corrections to occur. Insome situation, this effect may cause the system to cycle continuously,making the system useless for web guiding.

SUMMARY OF THE INVENTION It is, therefore, an object of the presentinvention to provide an air turning bar for moving webs that isadjustable in its position with respect to the web path and which avoidsthe difficulties of the prior art steerable turning bars. Another objectof this invention is to provide an air cushion web turning bar thatmoves the web simultaneously with movement of the bar. A further objectof this invention is to provide an air cushion. automaticallyadjustable, web turning bar that moves the web simultaneously with theturning bar when it moves to make a correction in web position. Anotherobject of this invention is to provide a means of isolating the effectsof downstream web position so that motion of the web does not hinder theoperation of the steerable turning bar system.

These and other objects and advantages of this invention areaccomplished by providing a turning bar whose position relative to theweb path is automatically adjustable in response to sensors detectingthe lateral position of the outgoing web, and a device for laterallyconstraining the outgoing web which is located near the turning bar andconstructed and arranged for simultaneous movement with the turning bar.The axis of movement of the lateral constraint device is in a directionthat is about perpendicular to the outgoing web path. This arrangementprovides stable, automatic web steering at high speeds and will maintainequal angular relationships between the incoming web path and the axisof the turning bar and the outgoing web path and the axis of the turningbar, so that tight and slack edges do not occur during steeringmovement.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a top plan view of a webturning apparatus emboyding this invention;

FIG. 2 is a side elevational view of the apparatus of FIG. 1;

FIG. 3 is a schematic illustration of an alternative embodiment of thisinvention; and

FIG 4. is a schematic illustration of turning bars for reversing webdirection DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT Referring nowto FIGS. 1 and 2 of the drawings wherein one embodiment is illustrated,reference numeral 10 denotes a frame or support for the web turningapparatus of this invention with the moving web 12 entering theapparatus from a coating or drying alley (not shown) or other webmanufacturing or processing equipment. To conserve floor space in thecoating or drying of wide webs of material, such as photographic film,and to provide for the unwinding and winding at the same end, thedirection of travel or path of web 12 must be reversed after passingthrough one half of the processing equipment.

In order to reverse the direction of travel of the web 12, it ispartially wrapped around an angularly placed turning bar 14 (FIG. 4) andthen around a second angularly placed turning bar 14. In one embodiment,a first turning bar 14 is placed at approximately a 45 angle to theoutside edge 13 of the incoming web 12' and the second turning bar 14 isplaced at approximately a 45 angle to the outside edge 15 of theoutgoing web 12". The axes of the two turning bars if extended to apoint of intersection would be at 90 to each other.

The turning bar 14 has a hollow, tubular body 16 having a substantiallyflat top surface 18, a substantially flat bottom surface 20, a curvedweb turning surface 22 joining one edge of each of the top and bottomsurfaces 18 and 20 and a sub stantially flat and vertically disposedside surface 24 opposite the turning surface 22 and joining the otheredge of each of the top and bottom surfaces. Other configurations ofturning bars, such as a cylindrical bar, may be used equally well. Eachof the top, bottom and turning surfaces 18, 20. and 22, are providedwith a multiplicity of perforations 26 through which air flows toprovide an air cushion for the web 12 in the conventional manner. Theaxis of the web turning bar 14 is positioned at approximately a 45 angleto the center line ofthe incoming web 12 in order that the web directionwill be changed 90 by passing over the top surface 18, the turningsurface 22, and the bottom surface 20, all in that order. The webdirection may also be changed by passing first over the bottom surface,then the turning surface and last over the top surface.

The air to provide the air cushion is supplied to the ends 28 and 29 ofthe turning bar 14 through elbows 30 and 31 connected by expansion ducts32 and 33 to a supply duct 34. This apparatus for supplying the cushionair is conventional and well known to those skilled in the art.

In order to correct or compensate for changes in the path of theincoming web, the turning bar 14 is movably positioned to reciprocateover a short distance along a path that is approximately laterallyperpendicular to the outgoing path 12" of the web 12. The turning bar 14is provided at each end 28 and 29 with a pair of bosses 36 each of whichcarries a bearing (not shown). A rod 38 extends between and beyond eachpair of bosses 36 and reach rod extends through the bearings. The rods38 are arranged with their axes approximately parallel to the centerline of the incoming web path 12 and are supported by being rigidlysecured to a pair of brackets 40 which brackets 40 are carried by asupport plate 42 afiixed to the frame 10.

With each end 28 and 29 of the turning bar 14 supported for slidingmovement on the rods 28, the turning bar 14 may then be moved orreciprocated to compensate for changes in the path 12' of the incomingweb. The turning bar 14 is moved by a piston rod 44 connected to ahydraulic actuator 46. The piston rod 44 is affixed to the flat sidesurface 24 of the turning bar 14. The actuator 46 responds to signalsfrom a controller 48 of conventional design which responds to signalsfrom one or more edge sensors 50 as will be explained hereinafter. Theturning bar 14 is illustrated for movement in a direction laterallyperpendicular to the outgoing web path. It should be understood that theturning bar may be supported for reciprocal movement in otherdirections.

The web 12 after passing around the turning bar 14' and changing itsdirection or path by 90 passes partially around a roller 52 located ashort distance downstream of the turning bar. The tension on the web andthe friction between the web and the roller results in the web beinglaterally constrained as it passes around the roller. The roller 52 isadapted for reciprocating, axial movement in a direction approximatelyparallel to the center line of the incoming web 12' and the axes of therods 38. The axis of the roller 52 is approximately normal to the edge15 ofthe web 12. One end 54 ofthe roller is supported by a ball bushingbracket 56 having a ball bushing (not shown) engaging a rod 58 supportedon the frame 10. The other end 60 of the roller 52 is rotatablysupported by a bracket 62 carried by the turning bar 14 in order thatthe roller 52 will move simultaneously with the turning bar. The lateralconstraint on the web insures that the web leaving the web turningapparatus or guider moves laterally by the same amount that the turningbar moves.

The edge sensors 50 are conventional pneumatic sensors which detect theposition of the edge of the web 12 before it comes into contact with thesurface 64 of the roller 52. The sensor or sensors may be locateddownstream of the roller 52. The sensors or sensor depending uponwhether center guiding or edge guiding is desired, are mounted on theframe 10 and they are adjusted for the desired position of the travelingweb in the conventional manner. If conditions upstream cause the web tomove out of its established path, the movement will be detected by theedge sensor or sensors. A signal or signals will be sent to thecontroller 48 in the conventional manner which signals are translatedinto directions to the hydraulic actuator 46 to change the position ofthe turning bar 14 to compensate for the change in web path.

In the prior art devices, changes in the position of the turning barwould initially affect a change in the path of the web which is lessthan the guider movement and would produce a skew in the path of the webnear the turning bar. In the apparatus of this invention the roller 52moves with the turning bar and simultaneously moves the web 12 by thesame amount. This movement of the roller 52 maintains the center line ofthe web 12" at a angle to the axis of the roller and insures thatmovement of the guider will not distort the angle between the centerline of the outgoing web 12" and the turning bar 14, nor the anglebetween the incoming web 12 and the turning bar 14, both of which arenormally about 45. This alignment will be maintained throughout movementof the turning bar 14 and the roller 52 in response to changes in theincoming path 12'.

Referring now to FIG. 3 wherein an alternative embodiment isschematically illustrated, the web 12 passes under the air cushionturning bar 14, around the curved surface 22 and over the top surface18, thereby changing its direction by approximately 90. movement of theturning bar in the direction of the arrows 76 is accomplished by thehydraulic actuator 46 operated by the controller 48.

Changes in the web position wherein the outgoing web path 12" is notheld at the desired lateral position are detected by the edge sensors 50which signal the controller to move the turning bar to return theoutgoing web to its proper position. A suction box 70 is located a shortdistance downstream from the turning bar and the suction box 70 ismounted for reciprocating movement in the direction of the arrows 78. Itis moved by being attached to the bracket 72 carried by the turning bar14. The suction box consists of three rollers 74 which cover a box inwhich a vacuum has been developed. The vacuum causes the web topartially wrap the rollers thereby developing the necessary traction toassure simultaneous lateral movement of the web with the rollers. Therollers may or may not be driven.

This web turning and guiding apparatus has been described wherein theweb path to the axis of the turning bar is at a 45 angle. It should beunderstood that the web path may be at other angles to the axis of theturning bar provided that the angle on the incoming side is equal to theangle on the outgoing side. Various arrangements may be utilized so longas the outgoing web path is perpendicular to the axis of the lateralconstraint or restraint that is simultaneously movable with thesteerable turning bar. It is preferred that the turning bar be of theair cushion type, however, other devices for changing the web directionsuch as polished bars or rollers may also be utilized.

The invention has been described in detail with particular reference topreferred embodiments thereof, but it will be understood that variationsand modifications can be effected within the spirit and scope of theinvention.

We claim:

1. In a steerable web turning bar assembly wherein the turning bar ismovable in a direction approximately laterally perpendicular to the pathof outgoing web leaving the turning bar, the improvement comprisinglateral constraint means for said outgoing web, said lateral constraintmeans being movable laterally and approximately perpendicularly withrespect to said outgoing web path and simultaneously with movement ofsaid turning bar. I A

2. The invention according to claim 1 wherein said lateral constraintmeans includes a movable roller supported a short distance downstream ofsaid turning bar and said web is partially wrapped about said roller.

3. The invention according to claim 1 wherein the path of the webentering the turning bar is at about a 90 angle to the path of theoutgoing web, and each of said paths is at about a 45 angle to the axisof said turning bar.

' 4. The invention according to claim 2 wherein support means areprovided for the movable turning bar which support means also supportsaid roller.

5. A steerable web turning and guiding apparatus c0mprising an aircushion turning bar adapted to change the direction of a web having anincoming path and an outgoing path, means supporting said bar forreciprocating movement in a direction approximately laterallyperpendicular to said outgoing path, lateral constraint means for saidweb in said outgoing path, said lateral constraint means being movablelaterally and approximately perpendicular with respect to said outgoingweb pathand simultaneously with movement of said turning bar.

6. A steerable web turning and guiding apparatus according to claim 5,wherein said lateral constraint means includes a movable rollersupported a short distance downstream of said turning bar and said webis partially wrapped about said roller.

7. A steerable turning and guiding apparatus for a moving web comprisinga turning device in the path of the web, said web path having anincoming portion and an outgoing portion with said turning deviceseparating said portions, said turning device being supported forreciprocating movement, a lateral constraint for said web in saidoutgoing portion, said lateral constraint being movable simultaneouslywith said turning device and in the same direction, and means for movingsaid turning device and lateral constraint to adjust the path of saidweb.

8. A steerable turning and guiding apparatus for a moving web accordingto claim 7 wherein said lateral constraint is movable by means carriedby said turning device.

9. A steerable turning and guiding apparatus for a moving web accordingto claim 7 wherein said lateral constraint means includes a movableroller supported a short distance downstream of said turning device andsaid web is partially wrapped about said roller.

10. A steerable turning and guiding apparatus for a moving web accordingto claim 7 wherein said lateral constraint means includes a suction boxhaving a plurality of rollers partially in contact with said web.

11 A steerable turning and guiding apparatus for a moving web accordingto claim 7 wherein said turning device and said lateral constraint aremovable in different directions.

1. In a steerable web turning bar assembly wherein the turning bar ismovable in a direction approximately laterally perpendicular to the pathof outgoing web leaving the turning bar, the improvement comprisinglateral constraint means for said outgoing web, said lateral constraintmeans being movable laterally and approximately perpendicularly withrespect to said outgoing web path and simultaneously with movement ofsaid turning bar.
 2. The invention according to claim 1 wherein saidlateral constraint means includes a movable roller supported a shortdistance downstream of said turning bar and said web is partiallywrapped about said roller.
 3. The invention according to claim 1 whereinthe path of the web entering the turning bar is at about a 90* angle tothe path of the outgoing web, and each of said paths is at about a 45*angle to the axis of said turning bar.
 4. The invention according toclaim 2 wherein support means are provided for the movable turning barwhich support means also support said roller.
 5. A steerable web turningand guiding apparatus comprising an air cushion turning bar adapted tochange the direction of a web having an incoming path and an outgoingpath, means supporting said bar for reciprocating movement in adirection approximately laterally perpendicular to said outgoing path,lateral constraint means for said web in said outgoing path, saidlateral constraint means being movable laterally and approximatelyperpendicular with respect to said outgoing web path and simultaneouslywith movement of said turning bar.
 6. A steerable web turning andguiding apparatus according to claim 5, wherein said lateral constraintmeans includes a movable roller supported a short distance downstream ofsaid turning bar and said web is partially wrapped about said roller. 7.A steerable turning and guiding apparatus for a moving web comprising aturning device in the path of the web, said web path having an incomingportion and an outgoing portion with said turning device separating saidportions, said turning device being supported for reciprocatingmovement, a lateral constraint for said web in said outgoing portion,said lateral constraint being movable simultaneously with said turningdevice and in the same direction, and means for moving said turningdevice and lateral constraint to adjust the path of said web.
 8. Asteerable turning and guiding apparatus for a moving web according toclaim 7 wherein said lateral constraint is movable by means carried bysaid turning device.
 9. A steerable turning and guiding apparatus for amoving web according to claim 7 wherein said lateral constraint meansincludes a movable roller supported a short distance downstream of saidturning device and said web is partially wrapped about said roller. 10.A steerable turning and guiding apparatus for a moving web according toclaim 7 wherein said lateral constraint means includes a suction boxhaving a plurality of rollers partially in contact with said web.
 11. Asteerable turning and guiding apparatus for a moving web according toclaim 7 wherein said turning device and said lateral constraint aremovable in different directions.